Module 2.1 - Bonding in Ceramics

Question 1

Attractive forces in ceramics are due to what?

Answer 1

Nature of bonding between atoms.

Question 2

Repulsive forces in atoms are due to what?

Answer 2

Interactions between the negatively charged electron clouds.

Question 3

What a system of 2 atoms is in equilibrium, what does this entail about the net force?

Answer 3

It has reached the point where the net force is 0, and the atoms are in critical distance.

Question 4

Equilibrium spacing occurs when?

Answer 4

Net force between two atoms is 0, and the bond energy is at a minimum.

Question 5

When is the bonding energy Eo at a minimum?

Answer 5

At the equilibrium spacing or when net force between two atoms is 0.

Question 6

When is the bonding energy Eo at a minimum?

Answer 6

At the equilibrium spacing or when net force between two atoms is 0.

Question 7

What are two types of bonds? Differentiate them.

Answer 7

Primary - chemical bonding
Secondary - Van der Waals

Question 8

How do secondary bonds occur?

Answer 8

they arise due to induced dipoles (can be temporary or permanent)

Question 9

What is the most electronegative element?

Answer 9

Fluorine

Question 10

When a bond has a higher electronegativity value, what does this entail about its ionic character?

Answer 10

More electronegative = more ionic character

Question 11

Do all ionic bonds have some covalent character?

Answer 11

Yes, all do.

Question 12

How come a purely ionic bond cannot exist?

Answer 12

Complete charge transfer is highly unfavorable, and this is because of the increase in kinetic energy.

Question 13

Ionic bonding is the _______ between electrons, while covalent bonding is _______ between electrons.

Answer 13

1. Transfer
2. Sharing

Question 14

What facilitates the transfer of electrons in ionic bonding?

Answer 14

Coulombic (electrostatic) attraction between the anion of one element, and the cation of one element.

Question 15

Ionic bonding causes materials to have a high melting point, to be hard and brittle, and to be electrically and thermally insulative. True or false?

Answer 15

True.

Question 16

What is the lattice energy?

Answer 16

Summation of all bonding energies with respect to a central atom.

Question 17

For electrostatic interactions, for the FIRST nearest neighbors, the central anion is attracted to the six neighboring cations at what distance?

Answer 17

r0

Question 18

For electrostatic interactions, for the SECOND nearest neighbors, the central anion is attracted to the six neighboring cations at what distance?

Answer 18

(sqrt of 2)(r0)

Question 19

For electrostatic interactions, for the THIRD nearest neighbors, the central anion is attracted to the six neighboring cations at what distance?

Answer 19

(sqrt of 3)(r0)

Question 20

Covalent bonding occurs between atoms that?

Answer 20

Have small differences in electronegativity

Question 21

Covalent bonding can be very strong or very weak. True or false?

Answer 21

True

Question 22

It is possible to predict mechanical properties through bonding alone. True or false?

Answer 22

False, it’s difficult to predict mechanical properties from bonding alone.